Air circuit breakers as described within U.S. Pat. Nos. 3,095,489 entitled "Manual Charging Means for Stored Energy Closing Mechanisms of Electric Circuit Breakers" and 3,084,238 entitled "Ratchet Mechanism for Charging a Closing Springs in an Electric Circuit Breaker" include operating mechanisms that are mainly exposed to the environment. Since the air circuit breakers are rated to carry several thousand amperes of current continuously, the exposure to convection cooling air assists in keeping the operating components within reasonable temperature limits.
Such air circuit breakers are usually provided with a motor operator such as described in U.S. Pat. No. 4,167,988 entitled "Ratcheting Mechanism for Circuit Breaker Motor Operator" or a manual handle as described in U.S. Pat. No. 3,729,065 entitled "Means for Charging A Stored Energy Circuit Breaker Closing Device" for charging the powerful closing springs contained within the air circuit breaker operating mechanism. As described within the aforementioned U.S. Pat. No. 4,167,988, the ratchet mechanism includes a driving pawl coupled with the motor operator for incrementally advancing a ratchet wheel coupled with the circuit breaker operating mechanism. Each incremental advance of the ratchet wheel is sustained by a holding pawl. Ultimately, the ratchet wheel is advanced to an angular position where the circuit breaker closing springs are fully charged and therefore empowered to forcibly close the circuit breaker contacts. Typically, the discharge of the closing springs rapidly drives the ratchet wheel in the same direction as did the driving pawl in charging the closing springs. In the process, the teeth on the ratchet wheel impact with the holding pawl, producing undue pawl and ratchet wear, as well as unnecessary stress on the pawl springs and mountings. Moreover, when the breaker contacts close, there is an inevitable rebound which tends to rotate the ratchet wheel in a reverse direction. Under these circumstances, the straight sides of the ratchet teeth impact against the straight edges of the holding pawl tip, causing potentially damaging stresses in the ratcheting mechanism. The patent further suggests the use of a holding prop to hold the pawl out of engagement with the ratchet wheel until the closing springs have filly discharged to protect the pawl and the ratchet wheel from potential damage. When the closing springs become discharged, the circuit breaker operating mechanism components are exposed to allow an operator to manually release the holding prop in order for the holding pawl to again become operative in re-charging the circuit breaker closing springs.
When a manual and motor controlled operating mechanism closing springs arrangement such as described in U.S. Patent Application Docket No. 41PR-7413 entitled "Ratcheting Mechanism for Industrial-Rated Circuit Breaker" filed concurrently herewith (May 27, 1997) is employed within an air circuit breaker operating mechanism, it is inconvenient for an operator to unlock the air circuit breaker enclosure to expose the operating mechanism components in order to manually access the closing prop.
Accordingly, one purpose of the instant invention is to provide a combined handle and motor operator for charging air circuit breaker closing springs by means of a ratchet and pawl arrangement. A further purpose of the invention is to hold the holding pawl away from the circuit breaker ratchet wheel during discharge of the circuit breaker closing springs to close the circuit breaker contacts. A still further purpose of the invention is to automatically return the ratchet and holding pawl into operative association with the circuit breaker closing springs charging shaft when the operating handle is later employed to charge the closing springs.